Response of Soil Microorganisms to As-Produced and Functionalized Single-Wall Carbon Nanotubes (SWNTs)

Environmental Science & Technology (Impact Factor: 5.33). 11/2012; 46(24). DOI: 10.1021/es303251r
Source: PubMed


The use of single-wall carbon nanotubes (SWNTs) in manufacturing and biomedical applications is increasing at a rapid rate; however data on the effects of a potential environmental release of the materials remain sparse. In this study, soils with either low or high organic matter contents as well as pure cultures of E. coli are challenged with either raw As-Produced SWNTs (AP-SWNTs) or SWNTs functionalized with either polyethyleneglycol (PEG-SWNTs) or m-polyaminobenzene sulfonic acid (PABS-SWNTs). To mimic chronic exposure, the soil systems were challenged weekly for six weeks; microbial activities and community structures for both the prokaryote and eukaryote community were evaluated. Results show that repeated applications of AP-SWNTs can affect microbial community structures and induce minor changes in soil metabolic activity in the low organic matter systems. Toxicity of the three types of SWNTs was also assessed in liquid cultures using a bioluminescent E. coli-O157:H7 strain. Although decreases in light were detected in all treated samples, low light recovery following glucose addition in AP-SWNTs treatment and light absorption property of SWNTs particles suggest that AP-SWNTs suppressed metabolic activity of the E. coli, while the two functionalized SWNTs are less toxic. The metals released from the raw forms of SWNTs would not play a role in the effects seen in soil or the pure culture. We suggest that sorption to soil organic matter plays a controlling role in the soil microbiological responses to these nanomaterials.

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    • "Compared with pure cultures and wastewater systems, the soil environment is much more complex and uncontrolled. When graphene enters the soil, it may interact with organic matter or clay minerals present in the soil [13], stabilizing graphene and making it less bioavailable, which would mitigate the effect of graphene on microbial communities. On the contrary, dissolved organic matter (DOM) might promote the mobility and bioavailability of graphene by acting as natural surfactants [14]. "
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